Parallel Optical Transmission Research Articles

Untwining multiple parameters at the exclusive zero-coincidence points with quantum control

In this paper we address a special case of ‘sloppy’ quantum estimation procedures which happens in the presence of intertwined parameters. A collection of parameters are said to be intertwined when their imprinting on the quantum probe that mediates the estimation procedure, is performed by a set of linearly dependent generators. Under this circumstance the individual values of the parameters can not be recovered unless one tampers with the encoding process itself. An example is presented by studying the estimation of the relative time-delays that accumulate along two parallel optical transmission lines. In this case we show that the parameters can be effectively untwined by inserting a sequence of balanced beam splitters (and eventually adding an extra phase shift on one of the lines) that couples the two lines at regular intervals in a setup that remind us a generalized Hong-Ou-Mandel interferometer. For the case of two time delays we prove that, when the employed probe is the frequency-correlated biphoton state, the untwining occurs in correspondence of exclusive zero-coincidence (EZC) point. Furthermore we show the statistical independence of two time delays and the optimality of the quantum Fisher information at the EZC point. Finally we prove the compatibility of this scheme by checking the weak commutativity condition associated with the symmetric logarithmic derivative operators.

Programmable Multiwavelength Achromatic Focusing and Imaging Through Scattering Media

Optical imaging and focusing through complex samples is a challenge with important applications in many fields. The critical problem is that turbid media such as biological tissue and multimode optical fibers randomly scatter and diffuse light, preventing the formation of diffraction-limited focus and image. We demonstrate with numerical simulations that a multiple scattering can be controlled via a serial optical transmission matrix and a parallel optical transmission matrix in order to obtain an achromatic focus and image at an arbitrary position. Simulation results of three-dimensional achromatic focusing and imaging based on this approach are agreed with the theoretical analysis. A scattering diffuser can be used as functional optical elements for focusing and imaging, moreover it can be manipulated and designed for multifunctional optical elements beyond traditional design. Our method will pave a way for using scattering media as unique optical achromatic elements for various applications, as well as for guiding the light and tailoring the light field.

An OE-VLSI for parallel optical interconnection

This paper presents a prototype OE-VLSI (Optoelectronic-VLSI) with 12-channel input and output ports for optical parallel link applications. The OE-VLSI comprises of a 12-channel parallel VCSEL (Vertical Cavity Semi-conductor Laser) array and a 12-channel parallel Photo Diode array, a CPU, a 12-channel VCSEL driver array and a 12-channel optical front-end amplifier. The 12×10Gbps VCSEL driver array and the optical front-end amplifier array are fabricated in 0.18μm CMOS technology. The chip was partitioned into 12 parallel channels to demonstrate chip-to-chip interconnection functions appropriate for applications of OE-VLSI technology. The OE-VLSI chip has been validated on an optical parallel transmission system with bit-error-rate BER less than 10−12 and an aggregate 120Gpbs bandwidth.

12‐Channel, 480 Gbit/s optical receiver analogue front‐end in 0.13 μm BiCMOS technology

A compact 12-channel 480 Gbit/s optical receiver analogue front-end (AFE) for parallel optical transmission systems has been implemented in 0.13 μm SiGe BiCMOS technology. The transimpedance amplifier of AFE employed common-gate amplifier and negative feedback structure to decrease input impedance and broaden bandwidth. The limiting amplifier adopted modified Cherry–Hooper amplifier with active feedback technique to stabilise current and acquire high gain simultaneously. Without on-chip spiral inductors, the spacing of adjacent channels is constricted to 250 μm and the chip area is only 3350 × 700 μm. With the psuedo-random binary sequence (PRBS) input data, the maximum operating rate of the AFE is 38.7 Gbit/s; meanwhile, the root mean square (RMS) jitter is 2.16 ps and the single-ended output amplitude of 183.7 mV is achieved. The power consumption of each channel is 150 mW from a 3.3 V supply.

Design of low power 4×40 Gb/s laser diode driver for parallel optical transmission systems

Design of low power 4×40 Gb/s laser diode driver for parallel optical transmission systems

A bit error rate analysis for TCP traffic over parallel free space photonics

Inter-satellite links (ISL) are a useful technology to transmit data to space stations and to communicate between satellites. However, there are serious limitations due to long delays and poor channel performance, resulting in high bit error rates (BER). In this paper, parallel transmission and the scaling of the Transport Control Protocol (TCP) window in free space optics (FSO) communications are analyzed in order to overcome these disadvantages in optical inter-satellite links. Latency and BER are the dominant effects that determine link performance. Thus, a physical, link, network and transport cross-layer analysis for FSO over ISL is presented in this paper. This analysis shows the advantages and disadvantages of using optical parallel transmission and TCP window scaling for free space optical links between stations and satellite constellations. The key contribution of this work is to simulate the effects of the BER and to link the results to packet error rate (PER) to determine the goodput for TCP transmissions by using a cross-layering approach. The results give evidence that wavelength division multiplexing (WDM) can mitigate the effects of long delay and high BER for a FSO communication using TCP.

Reconfigurable Parallel Plasmonic Transmission Lines With Nanometer Light Localization and Long Propagation Distance

A hybrid plasmonic parallel transmission line scheme constructed by a spatial single mode with time-domain multiline waveguide is presented in this paper. The proposed configuration enables a nanometer light localization while retaining a long propagation distance (~74 μm) at optical communication wavelengths with no crosstalk between data channels. High extinction ratio between the nanoribs peak energies (~20 dB) has been achieved after optimization. Furthermore, the proposed optical parallel transmission line scheme shows the advantages of enabling an optical device with a large number of parallel transmission channels, as well as a good robustness with respect to the fabrication tolerances.

4-channel, 40 Gb/s front-end amplifier for parallel optical receiver in 0.18 μm CMOS

This paper proposed a 4-channel parallel 40 Gb/s front-end amplifier (FEA) in optical receiver for parallel optical transmission system. A novel enhancement type regulated cascade (ETRGC) configuration with an active inductor is originated in this paper for the transimpedance amplifier to significantly increase the bandwidth. The technique of three-order interleaving active feedback expands the bandwidth of the gain stage of transimpedance amplifier and limiting amplifier. Experimental results show that the output swing is 210 mV (Vpp) when the input voltage varies from 5 mV to 500 mV. The power consumption of the 4-channel parallel 40 Gb/s front-end amplifier (FEA) is 370 mW with 1.8 V power supply and the chip area is 650 μm×1300 μm.

Optimized Parallel Transmission in OTN/WDM Networks to Support High-Speed Ethernet With Multiple Lane Distribution

The emerging high-speed Ethernet is expected to take full advantage of the currently deployed optical infrastructure, i.e., optical transport network over wavelength division multiplexing (OTN/WDM) networks. Parallel transmission is a viable option towards this goal, as exemplified by several IEEE and ITU-T standards. The optical virtual concatenation protocol in the OTN layer defined in ITU-T G.709 enables high-speed Ethernet signals to be decoupled into low rate virtual containers. The multiple lane distribution layer defined in IEEE 802.3ba facilitates the optical parallel transmission by stripping Ethernet signals into multiple low rate lanes which can be mapped onto optical channels. In this paper, we propose a new optimization framework for parallel transmission in OTN/WDM networks to support high-speed Ethernet. We formulate the parallel transmission optimization as an integer linear programming problem encompassing three sub-problems: parallel wavelength routing and assignment, usage of electronic buffering for skew compensation, and bufferless parallel transmission. To reduce computational complexity, we deploy multi-objective evolutionary optimization. The numerical results show that parallel transmission in OTN/WDM networks is feasible, and optimal solutions can be obtained with minimum resource consumption and bufferless system design.

High Reliability of High-Speed Vertical-Cavity Surface-Emitting Lasers with Silicone-Encapsulated Structure and Parallel Optical Transmitter Modules

Reliability of both high-speed vertical-cavity surface-emitting lasers (VCSELs) with silicone-encapsulated structure and the parallel optical transmitter modules were investigated. Results of wear-out life tests indicated that the VCSEL with a silicone-encapsulated structure has the same lifetime as a bare-chip VCSEL, which was more than 106 h at the junction temperature of 90 °C. High reliability of the 20 Gbps × 12 channel on-board parallel optical transmitter modules in various test environments was also confirmed.

High Reliability of High-Speed Vertical-Cavity Surface-Emitting Lasers with Silicone-Encapsulated Structure and Parallel Optical Transmitter Modules

High Reliability of High-Speed Vertical-Cavity Surface-Emitting Lasers with Silicone-Encapsulated Structure and Parallel Optical Transmitter Modules

Structural Study of Hole Assisted Fibers Considering Optical Parallel Transmission

Structural Study of Hole Assisted Fibers Considering Optical Parallel Transmission

Transmitters of Array-type LDs using Side-mode Injection Locking for High-speed LAN

This paper describes a study of transmitters of array-type Fabry-Perot laser diodes (FP-LDs) using side-mode injection locking. The transmitters are assumed to use in the previously proposed high-speed local area network (LAN), Para-Wave NET. Parallel optical transmission with a fiber ribbon and wavelength routing is used in the network. Array-type LDs must be simultaneously injection locked and then switched to another wavelength. The simultaneous injection locking and the wavelength switching have been investigated both experimentally and theoretically. We estimate acceptable cavity length deviation of LDs in an array by considering locking ranges. It is desirable to emit no power from an LD during switching or in the case of no-sending packets. However, it emits unnecessary power in the case of free run- ning states. Two possible methods to suppress free running states are investigated.

A Single-Chip CMOS-Based Parallel Optical Transceiver Capable of 240-Gb/s Bidirectional Data Rates

We report here on the design, fabrication, and high-speed performance of a parallel optical transceiver based on a single CMOS amplifier chip incorporating 16 transmitter and 16 receiver channels. The optical interfaces to the chip are provided by 16-channel photodiode (PD) and VCSEL arrays that are directly flip-chip soldered to the CMOS IC. The substrate emitting/illuminated VCSEL/PD arrays operate at 985 nm and include integrated lenses. The complete transceivers are low-cost, low-profile, highly integrated assemblies that are compatible with conventional chip packaging technology such as direct flip-chip soldering to organic circuit boards. In addition, the packaging approach, dense hybrid integration, readily scales to higher channel counts, supporting future massively parallel optical data buses. All transmitter and receiver channels operate at speeds up to 15 Gb/s for an aggregate bidirectional data rate of 240 Gb/s. Interchannel crosstalk was extensively characterized and the dominant source was found to be between receiver channels, with a maximum sensitivity penalty of 1 dB measured at 10 Gb/s for a victim channel completely surrounded by active aggressor channels. The transceiver measures 3.25times5.25 mm and consumes 2.15 W of power with all channels fully operational. The per-bit power consumption is as low as 9 mW/Gb/s, and this is the first single-chip optical transceiver capable of channel rates in excess of 10 Gb/s. The area efficiency of 14 Gb/s/mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> per link is the highest ever reported for any parallel optical transmitter, receiver, or transceiver reported to-date.

Parallel Optical Transmitter Module Using Angled Fibers and a V-Grooved Silicon Optical Bench for VCSEL Array

We propose an advanced structure of optical subassembly (OSA) for packaging of the vertical-cavity surface-emitting laser (VCSEL) array, using (111) facet mirror of the V-groove ends formed in a silicon optical bench (SiOB) and angled fiber apertures. The feature of our OSA can provide a low optical crosstalk between neighboring channels, a low feedback reflection, and a large misalignment tolerance along the V-groove. We describe the optimized design of fiber angle, VCSEL position, and fiber position. The fabricated OSA structure consists of 12 channels of angled fiber array, 54.7deg V-grooves, Au-coated mirrors on (111) end facet of the V-grooves, and flip-chip-bonded VCSEL array on a SiOB. In this structure, the beam emitted from the VCSEL is deflected at the 54.7deg mirror of (111) end facet and propagated into the angled fiber. The angled fiber array was polished by 57deg. Fabricated OSAs showed a coupling efficiency of 30%-50% that is 25 times larger than that obtained from an OSA with a vertically flat fiber array. Our OSA showed large misalignment tolerance of about 90 mum along the longitudinal direction in the V-groove. We fabricated a parallel optical transmitter module using the OSA and demonstrated 12 channels times2.5 Gb/s data transmission with a clear eye diagram

Implementation of active interposers for extremely high-definition display

This paper demonstrates a novel high-definition (HD) display system using the optical interconnection technique. This system features a 20-million-pixel 40-in thin film transistor (TFT) liquid crystal display (LCD) comprising four 20-in LCDs each with five million pixels. A four-channel optical interconnection module, called an active interposer, was employed to transmit graphical data consisting of red, green, blue, and clock signals. For efficient coupling with multimode fibers and to effect a compact coupling structure, three-dimensional (3-D) waveguide arrays with two-dimensionally (2-D) integrated optical input/output and optical path redirection to the pigtail connectors of the active interposer were applied. This paper also employed eight transmitter (Tx) and receiver (Rx) active interposers and 50-m multimode fibers in the system, and with 32-channel parallel optical data transmission successfully displayed HD pictures on the LCD. The results indicate that active interposers are suitable for graphical data transmission and show promise for future applications that use the optical interconnection technique.

10Gbit/s/channel パラレル光送信/受信モジュール

10Gbit/s/channel パラレル光送信/受信モジュール

Accurate Fiber Skew Measurements by a Phase Method

Recently, an optical parallel transmission using fiber ribbons has been investigated. The important parameter for optical parallel transmission systems is skew and recent fiber ribbon manufacturing technologies make the skew value low. Therefore, the accurate skew measurements for these low skew fiber ribbons become very important. In this paper, we discuss the accurate skew measurements by the phase method. Phase fluctuations are measured for two types of lasers, a DFB-LD and a FP-LD, to clarify the light source dependence. Phase fluctuations are also investigated theoretically, based on the lasing mode fluctuations (mode partition). Fluctuations using an ordinary single mode fiber and a dispersion shift fiber (DSF) are measured and the measured results are in good agreement with the theoretical ones.

An analog front-end chip set employing an electro-optical mixed design on SPICE for 5-Gb/s/ch parallel optical interconnection

A chip set composed of a laser-diode driver (LDD) and an optical receiver (RCV), which incorporates a full 2D (reshape, regenerate) function, has been developed by using silicon bipolar technology for a four-channel 5-Gb/s parallel optical transceiver. An electro-optical mixed design on SPICE of the LDD and the LD is accomplished by describing the rate equations of the LD as an electrical circuit. This design accommodates easy connectivity of the LDD chip to the LD in the optical transmitter module without the need for adjustment of the optical waveform. A pseudobalanced transimpedance amplifier (TIA) and feedforward automatic decision threshold control (ATC) in the RCV minimize the number of off-chip bypass capacitors, eliminate the need for any off-chip coupling capacitors, and keep crosstalk less than -50 dB and low cutoff frequency less than 80 kHz. A prototype parallel optical transmitter module and a prototype receiver module, based on the chip set, demonstrated asynchronous four-channel 5-Gb/s operation. The chip set has a throughput of 20 Gb/s with a power dissipation of 1.3 W at a 3.3-V supply.

Effect of Asymmetric Refractive-index Profile on Skew in Single-mode Fiber Ribbons

Low cost fiber ribbons with small skew value must be realized for high bitrate parallel optical transmission systems. The influence of asymmetric refractive-index profile is precisely investigated for this purpose. The previously proposed variational analysis can deal with the asymmetric profile. The accuracy of this analysis is checked theoretically and experimentally. The calculated skew values by the variational analysis are compared with ones by vector analysis using a multilayer approximation for symmetric profiles. The calculated values by the variational analysis are compared with the experimental data for asymmetric profiles. Considering the clarified accuracy of the analysis, skews of several asymmetric profiles are calculated. By measuring skew values of commercially available fiber ribbons, realization of low cost, small skew fiber ribbons is discussed.